Everyone looks thru sights/scopes differently.
Sorry; 'tain't true. That's one of many myths about the shooting sports.
With the single exception of someone's eye being off center in a scope's optical axis and that scope not focused at the target range, all the light from the target through the sights (scope and iron) is the same for everyone.
It's physically impossible for different eyes to see the relationship of the sights to the target for a given alignment with each other.
If you're referring to the situation when two people use different sight settings for the same rifle and ammo at a target, that's caused by each person holding the rifle differently. The rifle's movement during recoil while the bullet goes down the barrel will be different.